Energia da vibrazioni

Transcription

1 Energy harves,ng Energia da vibrazioni Luca Gammaitoni Dipar,mento di Fisica, Università di Perugia

2 Energy required to operate the portable devices Energy available from portable sources Source: IDTechEx, Energy Harves8ng and Storage , Cambridge EH: Energy Harves8ng; WSN: Wireless Sensors Network 2

3 Energy required to operate the portable devices We need to bridge the gap by ac,ng on both arrows Energy available from portable sources 3

4 Energy available from portable sources 4

5 Energy harves,ng basic ideas Unlimited source of free energy, readily available for mul,ple uses

6 Energy harves,ng basic ideas Energy res. Reality is slightly more complex Transduc)on sys. Dissipated energy Available energy

7 Energy harves,ng basic ideas Kine,c energy Focus on vibra,ons of solid bodies.

8 Vibra,ons energy harves,ng Energy budget Coupling/dynamic properties Energy res. Transduction properties Energy in the transd. Available Dissipative properties Heat sink

9 Vibra,ons energy harves,ng Dynamical model + - Energy transd. c Energy stored k m Energy dissipated γ x Vibra,ng body z

10 Vibra,ons energy harves,ng Dynamical model m x = du(x) dx γ x c(x,v ) + ζ z Where: U(x) γ x c(x,v ) ζ z Represents the Energy stored Accounts for the Energy dissipated Accounts for the Energy transduced Accounts for the input Energy

11 Vibra,ons energy harves,ng Dynamical model m x = du(x) dx V = F( x,v ) γ x c(x,v ) + ζ z Equa,ons that link the vibra,on- induced displacement with the Voltage

12 Vibra,ons energy harves,ng Dynamical model Equa,ons that link the vibra,on- induced displacement with the Voltage m x = du(x) dx V = F( x,v ) γ x c(x,v ) + ζ z Details depend on the physics of the conversion principles

13 Vibra,ons energy harves,ng Transduc,on mechanisms 1 Piezoelectric: dynamical strain is converted into voltage difference. 2 Capacitive: geometrical variations induce voltage difference 3 Inductive: dynamical oscillations of magnets induce electric current in coils 13

14 Vibra,ons energy harves,ng 1 Piezoelectric: dynamical strain is converted into voltage difference. m x = du(x) dx γ x c(x,v K V V + ) + ζ z ζ z V = KF( c x,v ) 1 V τ p The available power is propor,onal to V 2

15 Vibra,ons energy harves,ng 1 Piezoelectric: dynamical strain is converted into voltage difference. m x = du(x) dx γ x K V V + ζ z V = K c x 1 V τ p The Physics of piezo materials K c and K v depends on materials

16 Vibra,ons energy harves,ng 1 Piezoelectric: dynamical strain is converted into voltage difference. m x = du(x) dx γ x K V V + ζ z V = K c x 1 V τ p The oscillator dynamics U(x) is the elas,c poten,al mechanical energy of the oscillator

17 Vibra,ons energy harves,ng 1 Piezoelectric: dynamical strain is converted into voltage difference. m x = du(x) dx γ x K V V + ζ z V = K c x 1 V τ p The environmental energy available

18 What are fluctua)ons and how can we harvest them? The random character of kine,c energy ζ z Represents the vibra,on (force) What does it look like? At the micro-to-nano scales most of the energy available is kinetic energy present in the form of random fluctuations, i.e. noise. Thus the challenge is to: use the noise to power nano-scale devices aimed at Sensing/computing/acting and communicating.

19 The random character of kine,c energy Random vibrations / noise Thermal noise Acoustic noise Seismic noise Ambient noise (wind, pressure fluctuations, ) Man made vibrations (human motion, machine vibrations, ) All different for intensity, spectrum, sta,s,cs

20 Vibra,on database: RealVibra,ons It is very important that we can characterize the spectral features of the vibra,on we want to harvest Vibra)on sources digital library This Task is devoted to the realiza,on of database containing digital,me series and spectral representa,ons of experimentally acquired vibra,on signals. realvibra,ons.nipslab.org Signal presenta)on: Descrip,on Power spectrum Sta,s,cal data Time series download (authorized users)

21 New App for contribu,ng to the database Available on the App Store: RealVibra)ons

22 Vibra,ons energy harves,ng Linear systems Ambient energy Electric power Linear oscillator The transfer func,on is a math func,on of the frequency, in the complex domain, that can be used to represent the performance of a linear system For a linear system the transfer func,on presents one or more peeks corresponding to the resonace frequencies and thus it is efficient mainly when the incoming energy is abundant in that regions This is a serious limita,on when you want to build a small energy harves,ng system 22

23 For two main reasons Vibra,ons energy harves,ng (1) (2) the frequency spectrum of available vibra,ons instead of being sharply peaked at some frequency is usually very broad. The frequency spectrum of available vibra,ons is par,cularly rich in energy in the low frequency part and it is very difficult, if not impossible, to build small low- frequency resonant systems Acous,c noise quiete working env.

24 Micro energy harves,ng system 25 µm thick 1 mm high Freq. 10 KHz 100 µm Collabora,on with CEA- LETI Grenoble (FR)

25 Vibra,ons energy harves,ng Whish list for the perfect vibra,on harvester 1) Capable of harves,ng energy on a broad- band 2) No need for frequency tuning 3) Capable of harves,ng energy at low frequency 1) Non- resonant system 2) Transfer func,on with wide frequency resp. 3) Low frequency operated

26 Nonlinear noise harves,ng m x = du(x) dx γ x K V V + ζ z V = K c x 1 V τ p The oscillator dynamics Focus on the poten,al energy NON- Linear mechanical oscillators U(x) 1 2 ax 2

27 Nonlinear noise harves,ng Example Inverted pendulum This is a linear system! t sh s l m m deflection x strain bimorph piezo-bender l b m t p F. Coeone, PhD Thesys, Perugia 2007

28 Nonlinear noise harves,ng NON- Linear Inverted pendulum Y h m Δ permanents magnets M 2 l m m ξ(t) excita8on x d deflec8on M 1 r θ l b Piezo bender X b)

29 Nonlinear noise harves,ng NON- Linear mechanical oscillators hep:// Nonlinear Energy Harves,ng, F. Coeone; H. Vocca; L. Gammaitoni Phys. Rev. LeD., 102, (2009)

30 Nonlinear noise harves,ng NON- Linear mechanical oscillators U(x) = 1 2 k e x 2 + (Ax 2 + BΔ 2 ) 3 / 2 Nonlinear Energy Harves,ng, F. Coeone; H. Vocca; L. Gammaitoni, Physical Review Leeers, 102, (2009)

31 NON- Linear mechanical oscillators Nonlinear noise harves,ng Nonlinear Energy Harves,ng, F. Coeone; H. Vocca; L. Gammaitoni, Physical Review Leeers, 102, (2009)

32 Nonlinear noise harves,ng Duffing poten,al U(x) = 1 2 ax ax 4 b MAX = a 2 4D log(τ p ) L. Gammaitoni, I. Neri, H. Vocca, Appl. Phys. Lee. 94, (2009)

33 Monostable poten,al U(x) = ax 2n Nonlinear noise harves,ng Nonlinear oscillators for vibra8on energy harves8ng L. Gammaitoni, I. Neri, H. Vocca, Appl. Phys. Lee. 94, (2009) The benefits of noise and nonlinearity: Extrac8ng energy from random vibra8ons, Luca Gammaitoni; Igor Neri; Helios Vocca, Chemical Physics, Volume 375, p , (2010)

34 Nanomechanical nonlinear oscillators Sketch of a mul8- stable oscillator based on clamped membranes. The kine8c energy of the nonlinear vibra8on is converted into electric energy by either AlN or PZT membrane sandwiched between the electrodes. The voltage is then rec8fied by a nanodiode integrated to the SOI film

35 Educa,onal ac,vi,es Summer School July 2012, Erice (Sicily) 2013 Summer School "Energy management at micro and nanoscales" Perugia (IT), July 8-10,

36 A new devoted web site has been realized and opened at In the last two issues we have started a special session devoted to the publication of original scientific papers. Instruction for submission procedure is available at: The last issue has been distributed to more than 800 subscribers 36